"He'll pick it up and say, 'Hey Dada what are you doing? I love you,'" says Cook's fiancée LaQuana Norwood.

But no one is on the other line. Cook, at the age of 25, was shot and killed earlier this month in East Chicago as he shielded Antoine from gunfire, likely saving the young boy's life.

Cook, who had only recently come home from a year-long tour of duty in Afghanistan, was in his car on his way to visit his grandmother on Feb. 2 when a gunman opened fire on him and little Antoine. As bullets suddenly rained down on the car, Cook threw himself on top of the boy.

"When I got to his grandma's house they had rushed Antoine to the hospital already. He was in the emergency room," recalled Cook's fiancée Laquana Norwood in a phone interview with ABC News. "I didn't know where Will was. I saw his car outside. The police had everything taped off. After that I just rushed straight to the hospital and that's when I found out that Antoine had been shot in the left leg and a bullet had grazed his right leg and the right side of his head. They had found Will on top of Antoine."

It was Cook's heroism that likely enabled his son to survive despite a total of 15 shots fired in their direction.

"From my understanding when they started shooting, Will started taking off his seatbelt," Norwood said. "Antoine was sitting behind him. Will got grazed in the neck by a bullet and then when he turned around he got grazed again in the side. By the time he had completely turned around to shield Antoine that was when they hit Will in the back of the head. He was DOA."

Norwood, who said she and Cook were hoping to get married in June, noted that Cook's top priority was taking care of his family, including Antoine's older siblings, a 5-year-old sister and 6-year-old brother.

"I know he loved his kids and I figured that he probably felt like if you know, both he and Antoine couldn't make it, that at least he would make sure that Antoine would still be here with me," Norwood said.

Cook had been serving with the 713th Engineer Company, a unit that lost six of its members in Afghanistan. He returned home in late September. The incident that killed Cook, according to Norwood, was due to "mistaken identity." The assailants, she said, were seeking revenge for a shooting that had occurred earlier in the week.

The East Chicago Police Department did not respond to messages left by ABC News Friday.

Two weeks after the incident, Antoine is doing "a lot better" and is expected to make a full recovery, according to Norwood, but he is not walking yet.

"He won't be walking for a while," she said. "It will take at least six weeks just for the wound to heal. He's going to start physical therapy, but until his leg completely heals, he won't be walking. He has a lot of bullet fragments in his leg, but the doctors said they didn't go that deep in his skin so the older he gets they'll just start falling out or the doctors can take them out."

While the physical damage of the attack is evident, the psychological ramifications are harder to address.

"It's very hard to try to explain to the kids that their daddy is gone forever, especially at such a young age. Antoine, for him to see his dad taken away like that… he can't explain it, the only way he can express it is by the way he acts," Norwood said. "He's gotten very aggressive since then. He's acting out after what happened."

Whether it is the toy cell phone or photos of Cook around the house, Norwood said it is evident that Antoine misses his father.

"He always looks at his pictures," she said.

Norwood, along with Cook's brother, have started a trust fund in Cook's name. In a video on the fund's website, a tearful Norwood notes that Cook was "our hero until the end." To date they have raised nearly $4,000, one fifth of the way towards their goal of $20,000.